Conventional memories used in computers generally employ a method in which information stored in a memory is accessed by specifying the address corresponding to the location of the information in the memory. This type of memory device has a disadvantage in that data previously stored at a location may not be recovered once new information has been stored at the location. To solve this problem, associative memories have been developed wherein information is stored and searched on the basis of a reference input supplied from the outside. The reference input comprises part of the information stored or to be stored and all entries in the memory can be searched in one clock cycle.
Many associative memories have been developed and used as part of a computer memory, and are intended for storing electric digital signals. A scanning operation is necessitated when pattern information is involved, and this requires a much longer time in processing the data. It has been impossible to obtain outputs successively.